The present application relates to heavy vehicle parking systems, and is particularly directed to a parking apparatus for a heavy vehicle, such as a truck or tractor-trailer, during a loss of electrical power.
Vehicle parking systems for trucks are known. One type of vehicle parking system for trucks is an electronic parking brake (EPB) system. A typical EPB system includes an EPB valve which operates to maintain air brake system pressure and thereby to maintain parking brakes in released position. When a loss of electrical power occurs in known EPB systems when the vehicle is unparked, the parking brakes are maintained in the released position until the system pressure drops below a pop pressure associated with the EPB valve. The system pressure drops below the pop pressure in response to the truck driver pumping a foot valve to “fan down” the system pressure or other loss of system pressure. When the system pressure drops below the pop pressure associated with the EPB valve, the parking brakes are applied to park the truck in a manner as is known. It would be desirable to provide an EPB system in which the parking brakes are applied to park the truck upon a loss of electrical power without having the truck driver to pump the foot valve to fan down the system pressure below the pop pressure.